Optical lithography has been established as a cost-effective method for developing nanopatterns with feature dimensions of more than 100 nm. Such processes for developing nanostructures are also commonly termed nanoimprint lithography. Alternative methods for controlled patterning in the nanoscale range (in particular less than 100 nm) are generally inefficient and cost ineffective. These methods (e.g. electron beam lithography) require large initial capital outlays and have low throughput rates. This is especially true for the writing of dense patterns over substrates with relatively larger areas. While conventional lithography methods (e.g. photolithography) can be relied upon for low-cost fabrication of imprint molds for patterns with dimensions greater than the nanoscale range (in particular more than 100 nm), molds possessing nanofeatures require at the same time, the use of relatively expensive methods.
In general, nanoimprint lithography involves a top-down lithographic method for the development of nanostructures. The method can be employed to generate patterns with resolutions far superior to conventional lithographic techniques. Commonly, nanoimprint lithography methods can be classified into three main categories, namely, thermoplastic, photo nanoimprint lithography, and electrochemical nanoimprinting methods.
The nanoimprinting lithography technique has found popularity as an alternative means of creating nanopatterns, compared to conventional lithography means. Some of these disadvantages inherent in the latter include the need to replace costly consumables, high error rates and the limitation to approximately a 1 to 1 replication of the desired patterns.
While well-defined, functional metal oxide nanostructures developed through the lithography process are much desired in view of their large potential in commercial applications, many technical difficulties have been apparent in the pursuit of highly efficient and reliable methods of developing such metal oxide features. For example, in cases where chemical formulations comprising different forms of acrylates have been considered, the stability of the formulation is generally poor, due to the tendency for some of the components to experience early, undesired polymerization in the lithographic process.
Accordingly, there is a need to provide suitable lithographic processes which will provide the efficient and cost-effective development of functional metal oxide nanoparticles by overcoming or at least ameliorating the technical difficulties and disadvantages described above.